1. Field of the Invention
The present invention relates to an abnormality detecting device and an abnormality detecting method of an auger-type ice making machine for detecting an abnormality such as a freezing of an ice-scraping auger caused by an overgrowth of ice in a refrigerating cylinder.
2. Description of the Prior Arts
An auger-type ice making machine has conventionally been well-known wherein overcurrent is prevented from continuously flowing in an auger motor for driving an ice-scraping auger over a long period of time, in case that the ice-scraping auger becomes unrotatable because the auger is frozen due to an overgrowth of ice in a refrigerating cylinder. For example, Japanese Patent No. 2941112 discloses that an overcurrent breaker for cutting a circuit in response to overcurrent is provided on a path for supplying current to an auger motor, wherein the path for supplying current to the auger motor is cut by a protection device when an ice-scraping auger becomes unrotatable so that overcurrent flows in the auger motor.
Further, Japanese Examined Patent Publication No. HEI 4-24625 discloses a protection device that converts current flowing in the auger motor into voltage and controls to stop the driving of the auger motor when the converted voltage exceeds a predetermined voltage. In this latter protection device, the control for stopping the driving of the auger motor by the above-mentioned converted voltage is inhibited during a predetermined period from the start of the auger motor so as not to stop the driving of the auger motor due to great rush current upon the start of the auger motor.
In this type of auger-type ice making machine, in case where the ice-scraping auger becomes unrotatable due to the freezing of the ice-scraping auger, the auger does not completely become unrotatable, but an excessive load is intermittently given with respect to the rotation of the auger at its initial stage, i.e., at the time when the ice-scraping auger starts to freeze. Therefore, current flowing through the auger motor becomes excessive intermittently, i.e., a hunting starts to occur in the current flowing through the auger motor, with this state. However, the overcurrent breaker in the above-mentioned former conventional protection device does not respond to the hunting, since this protection device does not activate the overcurrent breaker with rush current at the start of the auger motor and instantaneous great current flowing through the auger motor, but activates the same only when great current flows through the auger motor over a long period to some extent. As a result, the above-mentioned former conventional protection device has a problem that a delay occurs in detecting an abnormality caused by the freezing of the ice-scraping auger in the auger-type ice making machine.
Further, the above-mentioned latter conventional protection device is required to stop the operation of the auger motor by activating the overcurrent breaker only when great current flows through the auger motor over a long period to some extent, since it prevents the auger motor from stopping with instantaneous great current like the former case. As a result, the above-mentioned latter conventional protection device also has a problem that a delay occurs in detecting an abnormality caused by the freezing of the ice-scraping auger in the auger-type ice making machine. Moreover, the latter protection device is required to count a time from the start of the auger motor for inhibiting the control to stop the operation of the auger motor during a predetermined time from the start of the auger motor.